1. Field of the Invention
The present invention relates to a rotary grinding tool including a housing, a drive motor arranged in the housing and having an output shaft projecting from the housing and having a grinding disc secured on its free end, and relates, in particular to a dust protection cover having a base fixedly securable with the housing and a substantially circular cover body connectable with the base for completely circumferentially covering the grinding disc and displaceable between an operational position, in which the cover body completely covers the grinding disc, and a release position in which the cover body exposes at least a portion of a grinding disc circumference.
2. Description of the Prior Art
For removing material from surfaces of constructional components formed of concrete, stone, or metal, a rotary grinding tool such as disclosed, e.g., in German Utility Model DE-297 17 099 UI, is used. The rotary grinding tool disclosed in DE-297 17 099 UI includes a housing, a drive motor arranged in the housing, a grinding disc mounted on the free end of the output shaft of the drive motor, and a two-part, circular dust protection cover. The dust protection cover covers the surface of the grinding disc facing the housing and circumferentially covers the grinding disc. The first part of the dust protection cover is formed by a base fixedly connected with the housing. The second part of the dust protection cover is formed by a cover body formed as a circular segment. The cover body is pivotally supported on the base for a pivotal movement about an axle extending transverse to the longitudinal axis of the motor output shaft. A suction nipple projects from the base. The nipple is connected with an external suction device for removing grinding waste from the cover.
In order to be able to grind, with this rotary grinding tool, in corners and other locations of the constructional component, which are accessible only with much difficulties, the cover body need be lifted off the base to expose the grinding disc. The drawback of the rotary grinding tool, which is disclosed in DE-297 17 099 UI, consists in that when, after being lifted off the base and not being used for awhile, the cover can become lost or the user cannot find it.
Accordingly, an object of the present invention is to provide a dust protection cover for a rotary grinding tool of the type described above which would provide for grinding in the corners and other locations of the constructional components accessible only with much difficulties, without a need to completely lift off the cover body from the base, i.e., without a danger of the cover body being lost.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing connection means projecting from a side of the base adjacent to the tool housing for securing the cover body to the base in the release position of the cover body.
Providing on the base connection means for securing the cover body to the base in the release position insures that the user does not need to look for the cover body after the cover body was moved to its release position. The positioning of the cover body on the base is effected rapidly and in a simple way because the connection means is arranged so that it is easily visible and accessible.
Advantageously, the connection means consists of at least one bolt extending parallel to the motor output shaft and on which the cover body is pinned up. In the preferred embodiment of the present invention, four bolts extend from the base in the direction of the housing. Two of the bolts, which are located more closely to the output shaft, have a greater length then two bolts located more remotely from the output shaft. The projection of the surface of the cover body taken parallel to the axis of the output or drive shaft has a shape of a substantially circular segment. The cover body has two clamping regions provided, respectively, at two oppositely spaced end regions. In a release position of the cover body, in which the cover body exposes a region of the circumference of the grinding disc, each clamping region is releasably mounted on a respective one of the two long bolts. The two bolts having a shorter length serve for securing the cover body with the base when the grinding disc is completely circumferentially covered by the dust protection cover.
To provide for a pivotal movement of the cover body from its operational position into its release position, when at least one bolt is used, the at least one bolt, which extends from the base toward the tool housing, forms a pivot axle and a guide for the cover body.
For displacing the cover body from its operational position into its release position, first, the cover body is displaced along the bolt toward the tool housing and then, after being lifted above the side of the base adjacent to the tool housing, is pivoted, by having its free end grasped, in a direction toward the output shaft of the drive motor, to its release position.
In order to provide for rapid and simple displacement of the cover body from its operational position to its release position, the connection means can be formed as a guide arranged substantially parallel to the diameter of the dust protection cover between the base and the cover body. The guide, e.g., can be formed of a guide channel provided, e.g., on the base, and a guide member displaceable along the guide channel and provided on the cover body. Alternatively, the guide channel can be formed in the cover body, with the guide member being provided on the base.
Advantageously, the dust protection cover is provided, at its end remote from the tool housing, with a collar projectable beyond the grinding surface of the grinding disc and formed of an elastic, air-permeable material, such as bristle. The collar forms a curtain between the free end of the dust protection cover and the surface of the constructional component to be treated.
The curtain, on one hand, prevents the grinding waste from leaving the dust protection cover and, on the other hand permits penetration of the outside air into the cover whereby interruption or breaking of the section flow generated by the external suction device is prevented.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.